Fixes for windows (#45)

* init Net system on Windows

* propagate DNS error

* Add zlib 1.2.11 sources

* link zlib statically for windows

* remove not implemented function declaration

* fix connect on Windows

test/IXTest.cpp

@@ -113,7 +113,7 @@ namespace ix
         }
 
         struct sockaddr_in sa; // server address information
-        socklen_t len;
+        socklen_t len = sizeof(sa);
         if (getsockname(sockfd, (struct sockaddr *) &sa, &len) < 0)
         {
             log("Cannot compute a free port. getsockname error.");

test/IXTest.h

@@ -52,6 +52,5 @@ namespace ix
 
     void log(const std::string& msg);
 
-    bool computeFreePorts(int count);
     int getFreePort();
 }